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The Nervous System
Jason, Luisa, Dan, and Sheila
The Nervous System
-The nervous system is an organ system that acts as the information
highway for the body and consists of many nerve cells (1).
-Nervous systems are made up of two cell types: neurons, and glial
cells(2).
-Neurons work to monitor the conditions in and around the body(1).
They give commands for responsive actions throughout the
organism(1).
Motor Neurons
A motor neuron is a type of neuron specialized to relay commands
from the brain or spinal cord to muscle cells, and gland cells (1).
Structure of a Motor Neuron (1)
- Dendrites, the " satellite
dishes"
They receive information
- The cell body
contains organelles present in
animal cells.
- The axon, " wiring"
They send information
- myelin sheath, " wire covering"
made of fats for insulation
Ions
-Major ions are K+ and Na+ (2)
-These ions cross the membrane through sodium and potassium
protein pumps (Na is pumped out, K is pumped in) (2)
-more sodium is pumped out than potassium in (2)
- Because of unequal pumping, a greater positive charge exists outside
of the neuron, while the cytoplasm inside the ion is negatively
charged (2)
Ions (cont.)
-At rest, the neuron is polarized with a negative charge (2)
-Active transport will cause the electronic imbalance to become larger and
gated channels will open (2)
-The neuron then becomes depolarized (more positive) (2)
-Pumps and potassium channels (which open) rebalance polarization (2)
Action Potential (2)
The process of depolarization and repolarization
- The Threshold level
(6)
Importance of Myelin
Myelin is imperative to proper
function of the human body.
Without this functional
insulation, the axons could no
longer effectively conduct
signals. This would result in
symptoms ranging from mild to
severe. (3)
Myelin Disorders
Demyelination: loss of myelin insulation.
(3)
-Multiple sclerosis,
acute
disseminated
encephalomyelitis, and
Guillain-Barré
Syndrome. (4)
Dysmyelination: insufficient or defective
myelin.(3)
- caused by genetic abnormailites
- leukodystrohies, schizophrenia (3)
Van Gogh was a notable
schizophrenic
References
1. Farabee, Mike. "the nervous system". Estrella Mountain Community College. Date Written Unknown.
Accessed 4 Nov. 2010. <http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.html>
2. Gregory, Michael. "Neurons". Clinton Community College. Date Written Unknown. Web. 4 Nov. 2010.
<http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/nervous
%20system/neurons.htm>
3. Unknown, Author. "Myelin." National MS Society. Date written unknown. Accessed 4 Nov. 2010.
<http://www.nationalmssociety.org/about-multiple-sclerosis/what-we-know-about-ms/what-isms/myelin/index.aspx>.
4. Unknown, Author. "Multiple Sclerosis." Internet Health Library. 5 Dec. 2006. accessed 4 Nov. 2010.
<http://www.internethealthlibrary.com/Health-problems/Multiple%20Sclerosis.htm>
5. Starr, Cecie, and Ralph Taggart. Diversity of life: Biology: The unity and diversity of life. 7. revised ed.
Belmont, Calif.: Wadsworth Publ., 1995. Print.
6. "YouTube- Action Potenital ." YouTube - Broadcast Yourself. . N.p., n.d. Web. 5 Nov. 2010.
<http://www.youtube.com/watch?v=SCasruJT-DU>.